The present invention relates to gas fuel for combustion devices and, more particularly, to a control system for controlling gas fuel flow to a combustion device to maintain a desired temperature.
Typically, most buildings, both houses and commercial, are built with various combustion devices for domestic hot water, interior heat, and other gas fired appliances. These devices include energy conversion units and distribution systems, often tank type storage units, namely gas or oil burners or electric elements; sets of controls, namely thermostats, thermocouples, electric valves and regulators; hot water storage tanks and heat exchangers; and conduits for transferring the heated water and air.
Most existing combustion devices heat water or air to or just greater than a desired temperature. The system then turns off for a period of time, until the water or air cools to a predetermined temperature below the desired temperature. The system then restarts and again heats the water or air.
Obviously, several problems and potential problems exist with such systems. For instance, turning the combustion device on and off can be expensive and inefficient. Additionally, wide fluctuations can occur in the gas fuel flow according to the demands on the system. Obviously, poor control of fuel flow can create negative responses from users, from mild annoyance to actual safety hazards. Additionally, on/off burner operation causes thermal shock to heat exchangers and combustion chambers, reducing the life of those parts.
It is seen then that there exists a need for a system and method for controlling gas fuel flow to a combustion device to maintain a desired water or air temperature, which overcomes the problems associated with existing systems which fluctuate up and down to keep achieving the desired temperature.